Actor Buck Henry will be telling a childhood story regarding Humphrey Bogart and other notable stars at a benefit on April 29. The invitation features a photo from the day in question of Bogie, left, and young Henry.Courtesy of Buck Henry

Buck Henry is hyping an April 29 benefit by promising he’ll reveal the story behind an intriguing childhood moment: The “afternoon I watched an amazing thespic parade consisting of Bogie, Peter Lorre, Sidney Greenstreet and Elisha Cook Jr. file out of a utility closet over and over again onto the set of ‘The Maltese Falcon,’ solemnly zipping their flies as they went.”

The event invitation features a photo from the day in question, of Bogie — Humphrey Bogart, of course — and a young Buck Henry.

It was taken circa 1940, long before Henry was nominated for two Academy Awards (for co-writing “The Graduate” and co-directing “Heaven Can Wait”) and hosted “Saturday Night Live” 10 times.

“We’re having a party to celebrate the Wooster Group and to start the endless, irritating money-raising that will be necessary to produce another round of . . . dramaturgical eccentricity,” Buck writes of the avant-garde theater collective, founded in 1975 by Elizabeth LeCompte, Willem Dafoe and others.

Ticket buyers are promised “a second letter with an explanation of how this photo came about and where the scary looking bruise on my forehead came from.”